Many manufactured or functional articles made in the form of a web or sheet, such as decals, reflective sheeting and labels, have one side intended to face a viewer (graphic side) and a back side on which is coated an adhesive (e.g., pressure sensitive adhesive (PSA) or heat activated adhesive). The adhesive coated side requires protection to prevent premature adhesion of the article to some substrate other than the desired one. That protection is often provided by a release liner, i.e. a sheet or web applied over the adhesive coated side which is easily removed and leaves the adhesive intact. Typical release liners are made of silicone coated paper or silicone coated film.
In the manufacture of the aforementioned functional articles, a release liner can sometimes be used. Release liners for use in a manufacturing process will be called process liners in this description. A process liner (e.g., paper or polyester film carrier web coated with a silicone, polyethylene or other release layer) can be coated with adhesive and laminated to a functional top film to produce an adhesive backed product. After the lamination, the adhesive adheres better to the functional top film than to the process liner; so that, when the process liner is removed, the adhesive remains with the functional sheet. These process liners are relatively expensive because the process for coating the release layer is expensive, and it adds another process step. The silicone or polyethylene release coating often does not adhere well to the carrier web, is transferred with the adhesive and remains as a contaminant on the back of the functional sheet.
The process liner is sometimes not an acceptable product liner for reflective or other functional sheetings due to deficiencies in dimensional stability, handling characteristics, cuttability or appearance. Release liners for finished adhesive coated articles will be referred to herein as product liners. Thus, the process liner for reflective sheeting can be replaced with a product liner in a separate process step. The product liner is often silicone coated or uncoated polyolefin film having good dimensional stability, handling, and appearance, but which can not withstand the high temperatures and mechanical stresses of the manufacturing process to which the process liner is exposed.
It would be highly desirable to have a release liner serve as both process and product liner.